Tyrosine-specific Phosphatase
   HOME

TheInfoList



OR:

Protein tyrosine phosphatases (EC 3.1.3.48, systematic name protein-tyrosine-phosphate phosphohydrolase) are a group of
enzymes An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as pro ...
that remove
phosphate Phosphates are the naturally occurring form of the element phosphorus. In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthop ...
groups from
phosphorylated In biochemistry, phosphorylation is described as the "transfer of a phosphate group" from a donor to an acceptor. A common phosphorylating agent (phosphate donor) is ATP and a common family of acceptor are alcohols: : This equation can be writt ...
tyrosine -Tyrosine or tyrosine (symbol Tyr or Y) or 4-hydroxyphenylalanine is one of the 20 standard amino acids that are used by cells to synthesize proteins. It is a conditionally essential amino acid with a polar side group. The word "tyrosine" is ...
residues on proteins: : proteintyrosine phosphate + H2O = proteintyrosine + phosphate Protein tyrosine (pTyr) phosphorylation is a common
post-translational modification In molecular biology, post-translational modification (PTM) is the covalent process of changing proteins following protein biosynthesis. PTMs may involve enzymes or occur spontaneously. Proteins are created by ribosomes, which translation (biolog ...
that can create novel recognition motifs for protein interactions and cellular localization, affect protein stability, and regulate enzyme activity. As a consequence, maintaining an appropriate level of protein tyrosine phosphorylation is essential for many cellular functions. Tyrosine-specific protein phosphatases (PTPase; ) catalyse the removal of a phosphate group attached to a tyrosine residue, using a cysteinyl-phosphate enzyme intermediate. These enzymes are key regulatory components in
signal transduction Signal transduction is the process by which a chemical or physical signal is transmitted through a cell as a biochemical cascade, series of molecular events. Proteins responsible for detecting stimuli are generally termed receptor (biology), rece ...
pathways (such as the MAP kinase pathway) and
cell cycle The cell cycle, or cell-division cycle, is the sequential series of events that take place in a cell (biology), cell that causes it to divide into two daughter cells. These events include the growth of the cell, duplication of its DNA (DNA re ...
control, and are important in the control of
cell growth Cell most often refers to: * Cell (biology), the functional basic unit of life * Cellphone, a phone connected to a cellular network * Clandestine cell, a penetration-resistant form of a secret or outlawed organization * Electrochemical cell, a de ...
, proliferation, differentiation,
transformation Transformation may refer to: Science and mathematics In biology and medicine * Metamorphosis, the biological process of changing physical form after birth or hatching * Malignant transformation, the process of cells becoming cancerous * Trans ...
, and
synaptic plasticity In neuroscience, synaptic plasticity is the ability of synapses to Chemical synapse#Synaptic strength, strengthen or weaken over time, in response to increases or decreases in their activity. Since memory, memories are postulated to be represent ...
.


Functions

Together with
tyrosine kinase A tyrosine kinase is an enzyme that can transfer a phosphate group from ATP to the tyrosine residues of specific proteins inside a cell. It functions as an "on" or "off" switch in many cellular functions. Tyrosine kinases belong to a larger cla ...
s, PTPs regulate the
phosphorylation In biochemistry, phosphorylation is described as the "transfer of a phosphate group" from a donor to an acceptor. A common phosphorylating agent (phosphate donor) is ATP and a common family of acceptor are alcohols: : This equation can be writ ...
state of many important
signalling A signal is both the process and the result of transmission of data over some media accomplished by embedding some variation. Signals are important in multiple subject fields including signal processing, information theory and biology. In ...
molecules, such as the
MAP kinase A mitogen-activated protein kinase (MAPK or MAP kinase) is a type of serine/threonine-specific protein kinases involved in directing cellular responses to a diverse array of stimuli, such as mitogens, osmotic stress, heat shock and proinflammato ...
family. PTPs are increasingly viewed as integral components of
signal transduction Signal transduction is the process by which a chemical or physical signal is transmitted through a cell as a biochemical cascade, series of molecular events. Proteins responsible for detecting stimuli are generally termed receptor (biology), rece ...
cascades, despite less study and understanding compared to
tyrosine kinase A tyrosine kinase is an enzyme that can transfer a phosphate group from ATP to the tyrosine residues of specific proteins inside a cell. It functions as an "on" or "off" switch in many cellular functions. Tyrosine kinases belong to a larger cla ...
s. PTPs have been implicated in regulation of many cellular processes, including, but not limited to: *
Cell growth Cell most often refers to: * Cell (biology), the functional basic unit of life * Cellphone, a phone connected to a cellular network * Clandestine cell, a penetration-resistant form of a secret or outlawed organization * Electrochemical cell, a de ...
*
Cellular differentiation Cellular differentiation is the process in which a stem cell changes from one type to a differentiated one. Usually, the cell changes to a more specialized type. Differentiation happens multiple times during the development of a multicellula ...
*
Mitotic Mitosis () is a part of the cell cycle in eukaryotic cells in which replicated chromosomes are separated into two new nuclei. Cell division by mitosis is an equational division which gives rise to genetically identical cells in which the t ...
cycles *
Oncogenic Carcinogenesis, also called oncogenesis or tumorigenesis, is the formation of a cancer, whereby normal cells are transformed into cancer cells. The process is characterized by changes at the cellular, genetic, and epigenetic levels and abno ...
transformation Transformation may refer to: Science and mathematics In biology and medicine * Metamorphosis, the biological process of changing physical form after birth or hatching * Malignant transformation, the process of cells becoming cancerous * Trans ...
*
Receptor endocytosis Receptor may refer to: *Sensory receptor, in physiology, any neurite structure that, on receiving environmental stimuli, produces an informative nerve impulse *Receptor (biochemistry), in biochemistry, a protein molecule that receives and responds ...


Classification


By mechanism

PTP activity can be found in four protein families. Links to all 107 members of the protein tyrosine phosphatase family can be found in the
template Template may refer to: Tools * Die (manufacturing), used to cut or shape material * Mold, in a molding process * Stencil, a pattern or overlay used in graphic arts (drawing, painting, etc.) and sewing to replicate letters, shapes or designs C ...
at the bottom of this article.


Class I

The class I PTPs, are the largest group of PTPs with 99 members, which can be further subdivided into * 38 classical PTPs ** 21
receptor tyrosine phosphatase Receptor tyrosine phosphatases are enzyme-linked receptor phosphatases, a family of protein tyrosine phosphatases. In humans, this family includes PTPRA, PTPRB, PTPRC, PTPRD, PTPRE, PTPRF, PTPRG, PTPRH, PTPRJ, PTPRK, PTPRM, PTPR ...
s ** 17 nonreceptor-type PTPs * 61 VH-1-like or dual-specific phosphatases (DSPs) ** 11 MAPK phosphatases (MPKs) ** 3 Slingshots ** 3 PRLs ** 4 CDC14s ** 19 atypical DSPs ** 5 phosphatase and tensin homologs (PTENs) ** 16
myotubularin Myotubularin domain represents a region within eukaryotic myotubularin-related proteins that is sometimes found with the GRAM domain. Myotubularin is a dual-specific lipid phosphatase that dephosphorylates phosphatidylinositol 3-phosphate and ...
s Dual-specificity phosphatases (dTyr and dSer/dThr) dual-specificity protein-tyrosine
phosphatase In biochemistry, a phosphatase is an enzyme that uses water to cleave a phosphoric acid Ester, monoester into a phosphate ion and an Alcohol (chemistry), alcohol. Because a phosphatase enzyme catalysis, catalyzes the hydrolysis of its Substrate ...
s. Ser/Thr and Tyr dual-specificity phosphatases are a group of enzymes with both Ser/Thr () and tyrosine-specific protein phosphatase () activity able to remove the
serine Serine (symbol Ser or S) is an α-amino acid that is used in the biosynthesis of proteins. It contains an α- amino group (which is in the protonated − form under biological conditions), a carboxyl group (which is in the deprotonated − ...
/
threonine Threonine (symbol Thr or T) is an amino acid that is used in the biosynthesis of proteins. It contains an α-amino group (which is in the protonated −NH form when dissolved in water), a carboxyl group (which is in the deprotonated −COO− ...
or the tyrosine-bound phosphate group from a wide range of
phosphoprotein A phosphoprotein is a protein that is posttranslationally modified by the attachment of either a single phosphate group, or a complex molecule such as 5'-phospho-DNA, through a phosphate group. The target amino acid is most often serine, threonin ...
s, including a number of enzymes that have been phosphorylated under the action of a
kinase In biochemistry, a kinase () is an enzyme that catalyzes the transfer of phosphate groups from high-energy, phosphate-donating molecules to specific substrates. This process is known as phosphorylation, where the high-energy ATP molecule don ...
. Dual-specificity protein phosphatases (DSPs) regulate mitogenic signal transduction and control the cell cycle.
LEOPARD syndrome Noonan syndrome with multiple lentigines (NSML) which is part of a group called Ras/MAPK pathway syndromes, is a rare autosomal dominant, multisystem disease caused by a mutation in the protein tyrosine phosphatase, non-receptor type 11 gene (''P ...
,
Noonan syndrome Noonan syndrome (NS) is a genetic disorder that may present with mildly unusual facial features, short height, congenital heart disease, bleeding problems, and skeletal malformations. Facial features include widely spaced eyes, light-colored ...
, and
metachondromatosis Metachondromatosis is an autosomal dominant, incompletely penetrant genetic disease affecting the growth of bones, leading to exostoses primarily in the hands and feet as well as enchondromas of long bone metaphyses and iliac crests. This syndr ...
are associated with ''
PTPN11 Tyrosine-protein phosphatase non-receptor type 11 (PTPN11) also known as protein-tyrosine phosphatase 1D (PTP-1D), Src homology region 2 domain-containing phosphatase-2 (SHP-2), or protein-tyrosine phosphatase 2C (PTP-2C) is an enzyme that in hu ...
''. Elevated levels of activated PTPN5 negatively affects synaptic stability and plays a role in
Alzheimer's disease Alzheimer's disease (AD) is a neurodegenerative disease and the cause of 60–70% of cases of dementia. The most common early symptom is difficulty in remembering recent events. As the disease advances, symptoms can include problems wit ...
,
Fragile X syndrome Fragile X syndrome (FXS) is a genetic neurodevelopmental disorder. The average IQ in males with FXS is under 55, while affected females tend to be in the borderline to normal range, typically around 70–85. Physical features may include a lo ...
,
schizophrenia Schizophrenia () is a mental disorder characterized variously by hallucinations (typically, Auditory hallucination#Schizophrenia, hearing voices), delusions, thought disorder, disorganized thinking and behavior, and Reduced affect display, f ...
, and
Parkinson's disease Parkinson's disease (PD), or simply Parkinson's, is a neurodegenerative disease primarily of the central nervous system, affecting both motor system, motor and non-motor systems. Symptoms typically develop gradually and non-motor issues become ...
. Decreased levels of PTPN5 has been implicated in
Huntington's disease Huntington's disease (HD), also known as Huntington's chorea, is an incurable neurodegenerative disease that is mostly Genetic disorder#Autosomal dominant, inherited. It typically presents as a triad of progressive psychiatric, cognitive, and ...
,
brain ischemia Brain ischemia is a condition in which there is insufficient bloodflow to the brain to meet metabolic demand. This leads to cerebral hypoxia, poor oxygen supply in the brain and may be temporary such as in transient ischemic attack or permanent i ...
,
alcohol use disorder Alcoholism is the continued drinking of alcohol despite it causing problems. Some definitions require evidence of dependence and withdrawal. Problematic use of alcohol has been mentioned in the earliest historical records. The World Hea ...
, and stress disorders. Together these findings indicate that only at optimal levels of PTPN5 is synaptic function unimpaired.


Class II

LMW (low-molecular-weight) phosphatases, or
acid phosphatases Acid phosphatase (EC 3.1.3.2, systematic name ''phosphate-monoester phosphohydrolase (acid optimum)'') is an enzyme that frees attached phosphoryl groups from other molecules during digestion. It can be further classified as a phosphomonoesteras ...
, act on tyrosine phosphorylated proteins, low-MW aryl phosphates and natural and synthetic
acyl In chemistry, an acyl group is a moiety derived by the removal of one or more hydroxyl groups from an oxoacid, including inorganic acids. It contains a double-bonded oxygen atom and an organyl group () or hydrogen in the case of formyl grou ...
phosphates. The class II PTPs contain only one member, low-molecular-weight phosphotyrosine phosphatase ( LMPTP).


Class III

Cdc25 Cdc25 is a dual-specificity phosphatase first isolated from the yeast ''Schizosaccharomyces pombe'' as a cell cycle defective mutant. As with other cell cycle proteins or genes such as Cdc2 and Cdc4, the "cdc" in its name refers to "cell divis ...
phosphatases (dTyr and/or dThr) The Class III PTPs contains three members, CDC25 A, B, and C


Class IV

These are members of the HAD fold and superfamily, and include phosphatases specific to pTyr and pSer/Thr as well as small molecule phosphatases and other enzymes. The subfamily EYA (eyes absent) is believed to be pTyr-specific, and has four members in human,
EYA1 Eyes absent homolog 1 is a protein that in humans is encoded by the ''EYA1'' gene. This gene encodes a member of the eyes absent (EYA) subfamily of proteins. The encoded protein may play a role in the developing kidney, branchial arches, eye, an ...
, EYA2, EYA3, and EYA4. This class has a distinct catalytic mechanism from the other three classes.


By location

Based on their cellular localization, PTPases are also classified as: * Receptor-like, which are
transmembrane receptors Cell surface receptors (membrane receptors, transmembrane receptors) are receptors that are embedded in the plasma membrane of cells. They act in cell signaling by receiving (binding to) extracellular molecules. They are specialized integral ...
that contain PTPase domains. In terms of structure, all known receptor PTPases are made up of a variable-length
extracellular domain An ectodomain is the domain of a membrane protein that extends into the extracellular space (the space outside a cell). Ectodomains are usually the parts of proteins that initiate contact with surfaces, which leads to signal transduction. A notabl ...
, followed by a
transmembrane A transmembrane protein is a type of integral membrane protein that spans the entirety of the cell membrane. Many transmembrane proteins function as gateways to permit the transport of specific substances across the membrane. They frequently u ...
region and a
C-terminal The C-terminus (also known as the carboxyl-terminus, carboxy-terminus, C-terminal tail, carboxy tail, C-terminal end, or COOH-terminus) is the end of an amino acid chain (protein or polypeptide), terminated by a free carboxyl group (-COOH). When t ...
catalytic Catalysis () is the increase in reaction rate, rate of a chemical reaction due to an added substance known as a catalyst (). Catalysts are not consumed by the reaction and remain unchanged after it. If the reaction is rapid and the catalyst ...
cytoplasmic The cytoplasm describes all the material within a eukaryotic or prokaryotic cell, enclosed by the cell membrane, including the organelles and excluding the nucleus in eukaryotic cells. The material inside the nucleus of a eukaryotic cell and ...
domain. Some of the receptor PTPases contain
fibronectin Fibronectin is a high- molecular weight (~500-~600 kDa) glycoprotein of the extracellular matrix that binds to membrane-spanning receptor proteins called integrins. Fibronectin also binds to other extracellular matrix proteins such as col ...
type III (FN-III) repeats,
immunoglobulin An antibody (Ab) or immunoglobulin (Ig) is a large, Y-shaped protein belonging to the immunoglobulin superfamily which is used by the immune system to identify and neutralize antigens such as pathogenic bacteria, bacteria and viruses, includin ...
-like domains, MAM domains, or
carbonic anhydrase The carbonic anhydrases (or carbonate dehydratases) () form a family of enzymes that catalyst, catalyze the interconversion between carbon dioxide and water and the Dissociation (chemistry), dissociated ions of carbonic acid (i.e. bicarbonate a ...
-like domains in their extracellular region. In general, the cytoplasmic region contains two copies of the PTPase domain. The first seems to have enzymatic activity, whereas the second is inactive. * Non-receptor (intracellular) PTPases


Common elements

All PTPases, other than those of the EYA family, carry the highly conserved active site motif C(X)5R (PTP signature motif), employ a common catalytic mechanism, and possess a similar core structure made of a central parallel
beta-sheet The beta sheet (β-sheet, also β-pleated sheet) is a common structural motif, motif of the regular protein secondary structure. Beta sheets consist of beta strands (β-strands) connected laterally by at least two or three backbone chain, backbon ...
with flanking
alpha-helices An alpha helix (or α-helix) is a sequence of amino acids in a protein that are twisted into a coil (a helix). The alpha helix is the most common structural arrangement in the secondary structure of proteins. It is also the most extreme type of l ...
containing a beta-loop-alpha-loop that encompasses the PTP signature motif. Functional diversity between PTPases is endowed by regulatory domains and subunits.


Expression pattern

Individual PTPs may be expressed by all cell types, or their expression may be strictly tissue-specific. Most cells express 30% to 60% of all the PTPs, however
hematopoietic Haematopoiesis (; ; also hematopoiesis in American English, sometimes h(a)emopoiesis) is the formation of blood cellular components. All cellular blood components are derived from haematopoietic stem cells. In a healthy adult human, roughly ten ...
and
neuronal A neuron (American English), neurone (British English), or nerve cell, is an excitable cell that fires electric signals called action potentials across a neural network in the nervous system. They are located in the nervous system and help to ...
cells express a higher number of PTPs in comparison to other cell types.
T cell T cells (also known as T lymphocytes) are an important part of the immune system and play a central role in the adaptive immune response. T cells can be distinguished from other lymphocytes by the presence of a T-cell receptor (TCR) on their cell ...
s and
B cell B cells, also known as B lymphocytes, are a type of the lymphocyte subtype. They function in the humoral immunity component of the adaptive immune system. B cells produce antibody molecules which may be either secreted or inserted into the plasm ...
s of hematopoietic origin express around 60 to 70 different PTPs. The expression of several PTPS is restricted to hematopoietic cells, for example, LYP,
SHP1 Tyrosine-protein phosphatase non-receptor type 6, also known as Src homology region 2 domain-containing phosphatase-1 (SHP-1), is an enzyme that in humans is encoded by the ''PTPN6'' gene. Function The protein encoded by this gene is a member ...
,
CD45 Protein tyrosine phosphatase, receptor type, C also known as PTPRC is an enzyme that, in humans, is encoded by the ''PTPRC'' gene. PTPRC is also known as CD45 antigen (CD stands for cluster of differentiation), which was originally called leukocy ...
, and HePTP. The expression of PTPN5 is restricted to the brain, and differs between
brain regions The human brain Anatomy, anatomical regions are ordered following standard neuroanatomy hierarchies. Physiology, Functional, Nervous system#Anatomy in vertebrates, connective, and Embryology, developmental regions are listed in parentheses wher ...
, with no expression in the cerebellum.


References


Sources

*


External links


PTP Summary and Relevant Publications
at
Monash University Monash University () is a public university, public research university based in Melbourne, Victoria (state), Victoria, Australia. Named after World War I general Sir John Monash, it was founded in 1958 and is the second oldest university in the ...
* * {{Portal bar, Biology, border=no EC 3.1.3